The present invention relates in general to route planning and navigation for road vehicles, and, more specifically, to determining preferred routes in response to roadway conditions that affect the ride quality felt by occupants in a vehicle following a route.
Roadway vehicles such as cars and trucks utilize dampers between the wheels and vehicle body to improve the ride comfort for the vehicle occupants. In addition to static damping systems such as traditional shock absorbers, adaptive (a.k.a. continuously-controlled) dampers have been introduced in which the damping automatically adjusts to match the driving conditions, resulting in a smooth, comfortable ride experience.
The ride behavior of a vehicle (i.e., vibration within the suspension/body system) is composed of two main components known as primary ride and secondary ride. Primary ride refers to body motion caused by a large bump or discontinuity. The suspension motion corresponding to primary ride is characterized by high amplitude and low frequency, such as a frequency range from about one to two Hz. Secondary ride refers to suspension motion having a lower amplitude and a higher frequency, such as around ten Hz., caused by smaller scale but more numerous imperfections in a road surface.
Especially for vehicles without adaptive damping, the ride comfort along some roads may be undesirable or unacceptable to some drivers. Thus, if a particular roadway was known in advance to have rough surfaces creating significant primary and/or secondary ride issues, then some drivers might choose to avoid them whenever reasonably possible.
Navigation systems for performing route planning to drive a vehicle to a desired destination are known which optimize potential routes according to various factors, such as travel time, travel distance, and maximum or minimum use of freeways. Ride quality, however, has not been available as a parameter for evaluating the desirability of different potential routes. Moreover, the supporting data needed to evaluate the ride comfort associated with different segments of roadway does not exist and would be expensive and time consuming to create.